Effective Dose of Crude Ethanol and Aqueous Extracts of Phytolacca Dodecandra (L’ Herit) on Anopheles Gambiae (Diptera: Culicidae) Larvae

Abstract

Objective: malaria vector control is either by adult or larvae management. This study reports on the effective dose of crude ethanol and aqueous extracts of leaf and mature green fruits of Endod; Phytolacca dodecandra (L’ Herit) as a larvicide against Anopheles gambiae (Diptera: Culicidae) mosquitoes. Material & Methods: Batches of twenty freshly hatched or moulted larvae (1st, 2nd, 3rd and 4th instars) of An. gambiae were transferred using droppers into plastic containers measuring 6 cm mouth and 5.7 cm base diameter by 3.5 cm height arranged in sets. Each container contained an approximate of 33 millilitre solution of a particular concentration of leaf (shoot or midsection) or fruit extracts of Endod. Endod plants were sourced from Nyando and Eldoret. The solutions were a serial dilution of 40, 20, 10, 5 and 5mg/100mls of the crude extracts. Solutions of Neem and deltamethrin were used as positive control and that of water only as negative control. Three replicates were set up for each concentration. WHO threshold of > 80 % mortality was used as standard to assess effectiveness of the larvicide. Results: Over 80% of all larvae (L1s, L2s, L3s and L4s) died from exposure to concentrations of 20mg and higher of ethanol extracts of mature green fruits of Endod irrespective of source. Only 40 mg/100 mls of aqueous extracts of Endod leaves of the shoot sourced from Eldoret killed > 80% of exposed L1s. Higher mortalities were observed for extracts from leaves of the shoot of Endod than those from the midsection. Conclusion: Higher doses of ethanol and water extracts of Endod leaves and fruits were lethal to all stages of An. gambiae larvae.